1. Field of the Invention
The present invention relates to a structure of a power storage apparatus including a plurality of stacked power storage devices.
2. Description of Related Art
An assembled battery may be configured by stacking a plurality of battery cells, for example. In this case, there may be formed a cooling space for cooling air to cool the battery cells between every two adjacent battery cells disposed in the stacking direction.
The assembled battery including the plurality of stacked battery cells has a higher thermal radiation in both end sections of the assembled battery than in a central section thereof in the stacking direction. For example, the battery cells located in the both end sections are adjacent to corresponding end plates, and the end plates function as radiator plates; therefore, the battery cells located in the both end sections have a higher thermal radiation.
Meanwhile, as disclosed in Japanese Patent Application Publication No. 2008-269985, each of the stacked battery cells may be provided with a cooling space through which cooling air flows so as to cool the battery cell. Unfortunately, acceptance of a cooling air flow also causes the air in the cooling space to flow out to the outside from an inflow port or an outflow port of the cooling air provided to the cooling space, which makes it difficult for the air to stay in the cooling space.
In such a case, in spite of introducing no cooling air, the air moving in the cooling space because of natural convection flows out to the outside of the cooling space; therefore, in a lower-temperature environment, the battery cells located in the end sections having a higher thermal radiation are further cooled.
If variation in temperature in the stacking direction among the plural battery cells becomes greater, it becomes difficult to sufficiently exert a battery performance of the entire assembled battery. This is because an internal resistance becomes increased at a lower temperature in each battery cell, and thus a voltage behavior becomes greatly changed.